Summary form only given, as follows. People have been dealing with complex systems since the dawn of time. They have tried to predict the weather, cure disease and interact with society, even in the most primitive of times. This talk argues that we (humans) have approached complex systems using a standard approach, utilizing the following steps: (1) collect data from (make observations of) the sys...
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This paper introduces TUTW - Temporal Uncertainty Time Warp - a control engine designed for an exploitation of temporal uncertainty (TU) in general optimistic simulations, and concentrates on an agent-based implementation of TUTW which enables distributed simulations over the Internet. A novel concept in TUTW is an event model where time intervals are attached to events instead of classical punctu...
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Simulations often need access to physically distributed data resources such as datasets, sensors, or even other simulations. The Agent-Based Environment for Linking Simulations (ABELS) is a framework that allows distributed simulations and data resources to dynamically communicate with each other in real time to produce useful and accurate results. Specifically, it allows independently designed si...
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This paper addresses the problem of excessive memory usage in simulators using asynchronous conservative parallel discrete event simulation algorithms. The characteristics of the modeled system that promote this problem are examined. Existing algorithms that attempt to solve this problem are discussed and new flow control algorithms introduced. Results of simulation experiments using both existing...
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Clusters of workstations have emerged as a cost effective solution to the high performance computing problem. To take advantage of any opportunities, however, effective scheduling techniques are necessary that enable parallel applications to dynamically share workstations with their owners. In this paper a special type of parallel applications called gangs are considered. Gangs are jobs that consi...
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Modelica is a general equation-based object-oriented language for continuous and discrete-event modeling of physical systems for the purpose of efficient simulation. The language unifies and generalizes previous object-oriented modeling languages. It is bringing about a revolution in this area, based on its ease of use, visual design of models with combination of Lego-like predefined model buildin...
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The data traffic in wireless networks for the third generation (3G) mobile telecommunication systems should take into account a variety of services (voice, data, video) and environments (e.g.: private, outdoors, indoors) as well as the user mobility behavior. A good evaluation of measures of performance can help a system designer to make strategic decisions concerning cell size and the number of c...
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We demonstrate the capability of optical buses in enabling orders of magnitude greater bandwidth between the processor and off-chip memory in a uniprocessor computer system. Through a simulation-based performance analysis of a 1 GHz processor model, we provide a preliminary evaluation of the benefits of an optical processor-to-memory bus in both eliminating the bandwidth bottleneck and in reducing...
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The performance of a parallel simulation system depends very much on partitioning simulation workload evenly among the set of processors in the computing environment to ensure load-balance between processors. Most parallel simulation systems employ user-defined static partitioning. However static partitioning requires in-depth domain knowledge of the specific simulation model in the study. It is n...
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In this paper, the principle of facial animation compatible with the MPEG-4 standard is introduced. Then the algorithm of calculating the displacements of face mesh vertices within the influence of facial animation parameters (FAPs) is discussed and improved. At last, a method of constructing FaceDefTables, which is one field of facial definition parameters (FDPs), is presented Using this techniqu...
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Graphical user interfaces can provide interactive and intuitive visual communication to fault simulation and analysis application programs, enhancing the capabilities of engineers to conduct studies with ease and flexibility. Unfortunately, such benefits often come at the price of efficient CPU utilization and more complicated maintenance activities. Employing a distributed architecture can mitiga...
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The emergence of mixed-signal (analog and digital) integrated circuits motivates the need for CAD tools supporting mixed-signal design and analysis. Furthermore, the presence of a large body of existing models in existing modeling language and the need for modeling mixed-signal (analog and digital) circuits motivates the need for a single unified simulation framework into which different parallel ...
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CSIM18 simulation models are often built as Microsoft Windows console-mode programs. A tool named REMOTE was developed to enable automatic, remote execution of CSIM18 models (and of other console mode programs) in a Windows environment. A master PC distributes the programs to remote PCs and collects the output files as the remote model executions complete. The status of remotely executing models c...
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One of the major challenges faced by designers of ad hoc network systems is the deployment of end-to-end quality-of-service support mechanisms. This paper describes QoS-AODV, an integrated route discovery and bandwidth reservation protocol. QoS-AODV is designed to operate within a TDMA network. Unlike other path finding and route discovery protocols that ignore the impact of the data link layer, Q...
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With the increasing number of mobile users, the network traffic for tracking mobile hosts is expected to increase dramatically, thus an efficient protocol for IP mobility support is of great value. We study the performance of such protocols. Starting from identifying the shortcomings in current evaluation methods and presenting the unfitness to our topic in current network simulators, we make thre...
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In order to support realistic real-world processes, workflow systems need to be able to adapt to changes. Detecting the need to change and deciding what changes to carry out are very difficult. Simulation analysis can play an important role in this. It can be used in tuning quality of service metrics and exploring "what-if" questions. Before a change is actually made, its possible effects can be e...
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Carrier Sense Media Access (CSMA) protocol is a widely used algorithm to control the access of a computer to the shared media (channel). There are several variants derived from this Media Access Control (MAC) method, such as non-persistent CSMA, 1-persistent CSMA, p-persistent CSMA, and CSMA/CD etc. These algorithms are successful in time-insensitive network, such as Ethernet. But for the fieldbus...
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Supply chain management (SCM) is a series of activities, usually sequential, that an organisation, or a network of organisations, uses to deliver products and/or services to customers. With the globalisation of commercial markets, distributed supply chain (DSQ) simulation, connecting organisations from various parts of the world, has gained significance in supply chain management decision support....
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This article presents an approach and tool for specification simulations accomplished in the formal description technique (FDT) enhancements to language of temporal ordering specification (E-LOTOS). Based on the defined inference rules for the E-LOTOS operators, the tool offers resources for interactive simulation, enabling the user to monitor the specification behavior. To illustrate the use of t...
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This paper discusses the design and implementation! of Simm-cast, an object-oriented framework for network simulation with specific support for group communication. The design of the framework is focused towards simplicity and extensibility. The aim is to allow a spectrum of experiments ranging from evaluation of abstract group communication models to simulation of more detailed multicast protocol...
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The use of wireless communications networks has gained phenomenal momentum both in the business and individual-user sectors. As a consequence of the increasing reliance of businesses on such networks, service disruption due to network facility failures can cause severe economic impact on the associated business. Hence service survivability-i.e., providing continued service in the midst of network ...
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Ad hoc networks are useful for providing communication support where no fixed infrastructure exists or the deployment of a fixed infrastructure is not economically profitable, and movement of communicating parties is allowed. Therefore, such networks are designed to operate in widely varying environments, from military networks to low-power sensor networks and other embedded systems. Frequent topo...
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